As further advances are made in computerization, attention has been focused on the development of devices such as an e-paper display that is small in thickness and light in weight, so as to be capable of substituting for paper, an IC-tag capable of instantaneously identifying merchandise one by one, and so forth. As a switching element in those devices, use is currently made of a thin-film transistor wherein amorphous silicon (a-Si) or polycrystalline silicon (p-Si) is used for semiconductor. However, manufacturing of the thin-film transistor using those silicon-based semiconductors will not only cause an increase in manufacturing cost because of the necessity of installing an expensive plasma enhanced chemical vapor deposition (CVD) system, sputtering system, and so forth, but also cause the inconvenience of lowering throughput because of the necessity of going through respective processes of vacuum process, photolithography, additional working, and so forth.
Accordingly, attention has since been focused on the development of an organic thin-film transistor, and an oxide thin-film transistor, with an organic matter and a metal oxide, used in a semiconductor layer, respectively, since those thin-film transistors can be formed by use of a coating method, or a printing method, thereby enabling products thereof to be provided inexpensively.
In order to enhance a working speed of the thin-film transistor described as above, and a working speed of a circuit wherein the plural thin-film transistors are connected with each other to be assembled, it is necessary not only to enhance field effect mobility of the thin-film transistor but also to lessen parasitic capacitance occurring to overlapping parts between a gate electrode and source•drain electrodes.
There has been known a technology (refer to JP-A-2004-241397 given hereunder) whereby source•drain electrodes are formed at respective protrusions formed on a substrate, by means of photolithography, respectively, a channel and a gate are formed in a recessed region between the protrusions, and the source•drain electrodes and a gate electrode are formed in a self-aligned fashion, thereby forming a thin-film transistor that has successfully lessened parasitic capacitance occurring to overlapping parts between the gate electrode and the source-drain electrodes.
Further, there has also been known a technology (refer to JP-T-2006-510210 given hereunder) whereby source•drain electrodes and a gate electrode are formed in a self-aligned fashion by means of a printing method utilizing embossing, thereby forming a thin-film transistor that has successfully lessened parasitic capacitance occurring to overlapping parts between the source•drain electrodes, and the gate electrode.